Step 1: Materials
1) A packet of ketchup
2) Your friends drink (best if it's dark like Pepsi or A cup that isn't see through)
3) A straw
4) Your friend
Step 2: The Main Part
With the ketchup, rip of the little corner that says, Tear Here, or the Purple Line. Make sure you don't rip it to close to the top or else the straw won't fit in the packet.
Step 3: The Hard Part
WARNING!!! MAKE SURE YOU DON"T RUSH THROUGH THIS STEP BECAUSE IF THE KETCHUP COMES OFF THE STRAW, IT IS A BIG PROBLEM!!!
Step 4: Sit Back and Relax
1) The Ketchup Will Go Up The Straw Into The Persons Mouth When They Try To Drink
2) Nothing will come up the straw at all.
It is so much fun watching your friend trying to drink the liquid while you just sit there trying not to laugh.